1. Field of the Invention
The present invention relates to digests for electronic files and, more particularly, to use of digests in file management systems.
2. Description of Related Art
File management systems can make use of hash or digest values when managing electronic files. The management of electronic files can vary depending on the application. For example, the management may provide document retention for electronic files. As another example, the management may provide file security to restrict access to electronic files.
Hash or digest values are often used to identify electronic files or as a representation (e.g., signature) of their contents. Hash or digest values are also often used to identify or authenticate files. Unfortunately, whenever an electronic file is changed the hash or digest values must again be determined. Computation of hash or digest values can be burdensome when the electronic documents are changed because the computations must be repeated each time. In the case of encrypted documents, the overhead associated with providing hash or digest values can be particularly burdensome. For example, it is inefficient to have to decrypt an entire encrypted file and then subsequently produce the hash or digest values as well as again encrypt the electronic file when only a part of the electronic file has been modified.
Therefore, there is a need for improved approaches to produce hash or digest values for electronic documents.